Rubberized roof underlayment

ABSTRACT

An underlayment product comprises a fibrous mat having an upper surface and a lower surface. A rubberized asphalt coating is applied to the lower surface of the fibrous mat and extends at least partially into the fibrous mat. An oxidized asphalt coating is applied to the upper and lower surfaces of the fibrous mat generally encapsulating the fibrous mat including the rubberized asphalt coating provided on the lower surface of the fibrous mat. The oxidized asphalt layers may be coated with a release layer such as talc, granules or a polymer.

TECHNICAL FIELD

The present invention relates to roof underlayments and more particularly, to a heavyweight, underlayment product which utilizes a rubberized asphalt layer.

BACKGROUND INFORMATION

An underlayment material is commonly used in a number of roofing applications as well as other underlayment situations. The typical product utilized in roofing underlayment is commonly referred to as “tar” of “felt” paper. The traditional “tar paper” is an asphalt impregnated paper product which is sold in a roll; unrolled on a roof; cut to length; and fastened to the roof utilizing staples or nails. Although tar paper is inexpensive, it does not seal nail holes through the paper and thus does not prevent water infiltration. In addition, once the felt is rolled out, it absorbs water and once wet, it wrinkles and expands, and must be allowed to dry out before covering with shingles. Other prior art shingle underlayment products also suffer from the same problems.

Accordingly, what is needed is a generally low cost, heavyweight, dimensionally stable underlayment product on which the installer can walk, without sticking or slipping, which will not slide underfoot and which will cold flow and/or elongate and recover to seal nail holes and other punctures. In addition, such a product should be dimensionally stable, resist tearing, non-adhesive to other layers, and provide hot and cold flexibility.

SUMMARY

The present invention features a novel underlayment product which will be relatively inexpensive and replace prior art products such as “tar paper” or “felt paper”. The present invention provides an underlayment product with a top surface that can be walked on and will not slide under foot, and wherein the product will not stick to itself or the roof. In addition, the present invention has “cold” flow properties which allow it to “repair” or “heal” itself to thereby reseal around nail or puncture holes and also elongate and recover around punctures.

In accordance with one embodiment of the present invention, the underlayment includes an underlayment membrane comprising a fibrous mat having an upper surface and a lower surface. An elastomeric asphalt coating is applied to the lower surface of the fibrous mat and at least partially or fully infiltrates and saturates the fibrous mat. Next, an oxidized asphalt coating is applied to both the upper and lower surfaces of the fibrous mat, thereby essentially encapsulating the fibrous mat.

The underlayment membrane may further include a release coating applied to the oxidized asphalt coating on either the upper and/or lower surface of the fibrous mat. The release coating includes, in one embodiment, a talc/water coating but may alternatively include granule particles applied proximate at least the oxidized asphalt coating proximate said upper surface of said fibrous mat.

The release coating may include a polymeric coating applied on at least the upper surface of the fibrous mat while the polymeric coating may be provided with a coating of finally-ground mineral, such as talc and finely-ground granules.

In the preferred embodiment, the rubberized asphalt coating which is applied from the bottom of the mat and partially or fully infiltrates the fibrous mat includes approximately 48% flux asphalt, 2% radial SBS rubber and 50% filler material while the fibrous mat includes fibers selected from the group consisting of polyesters, polypropylenes and fiberglass. The coating may, however, be provided having a range a ingredients including, but not limited to 0.5% to 12% radial or linear rubber or polymer; 0-70% filler; and 48-98% asphalt including 0-70% oxidized asphalt. The filler affects the walkability of the outer surface. If the filler content is too low such that a higher asphalt percentage exists, the product would be sticky. The high filler content and/or talc layer prevents sticking. In addition, the filler also brings down the price of the finished product.

Adding an oxidized asphalt layer on both the top and bottom layer of the mat makes the product more usable in hotter conditions providing a higher resistance to softening by providing an asphalt with a higher Ring and Ball softening point temperature. It also makes the product not stick in three ways: 1) foot traffic 2) the roof deck and 3) in the roll form.

The rubber or other elastomer in the elastomeric layer may be linear or radial rubber although with linear SBS rubber, as much as 10 or 12 percent may be required whereas with radial SBS rubber, 0.5 to 6% will generally suffice.

In the preferred embodiment, the talc coating is suspended in a water-based, polymer emulsion. Examples of the polymer include styrene, acrylic and the polyurethane. When it dries, the polymer forms a film which helps hold the talc to the asphalt so that the talc does not fall off or interfere with any overlap or bonding areas. Loose talc is a slip problem. Although a talc acrylic layer is preferred as the method to prevent sticking, a water or other based polymer may be applied and may be sufficient, as would be a plastic film.

It is important to note that the present invention is not intended to be limited to a system or method which must satisfy one or more of any stated objects or features of the invention. It is also important to note that the present invention is not limited to the preferred, exemplary, or primary embodiment(s) described herein. Modifications and substitutions by one of ordinary skill in the art are considered to be within the scope of the present invention, which is not to be limited except by allowed claims.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will be better understood by reading the following detailed description, taken together with the drawings wherein:

FIG. 1 is a schematic sectional view of the underlayment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention features a novel underlayment product which will be relatively inexpensive and replace prior art products such as “tar paper” or “felt paper”. The present invention provides an underlayment product with a top surface that can be walked on and will not slide under foot, and wherein the product will not stick to itself or the roof. In addition, the present invention has “cold” flow properties and elongate and recovery properties which allow it to reseal around nail or puncture holes.

The underlayment 10, FIG. 1, in accordance with the present invention includes a fibrous mat 12 disposed in the center of the underlayment. Examples of and equivalents for the fibrous mat 12 are disclosed in U.S. Pat. Nos. 6,531,200 and 6,296,912 assigned to the assignee of the present invention and incorporated fully herein by reference.

The fibrous mat 12 is first coated proximate one side with a rubberized asphalt layer 14. The rubberized asphalt layer 14 typically comprises approximately 4% rubber, 46% flux asphalt and 50% filler, although various percentages may be provided. These percentages are approximate and those skilled in the art would understand that a deviation from these percentages is considered within the scope of the present invention.

The rubberized asphalt layer 14 exhibits “cold flow” or “self-healing” properties by virtue of the inclusion of a relatively small percentage of rubber. Accordingly, when the underlayment 10 is punctured, such as by a nail, the rubberized asphalt layer 14 will “self-heal” around the puncture thereby resealing around the puncture. This is particularly important when underlayment is used under roofing tile in which case the tiles are fastened to the roof using “ring” nails which create a hole which is larger than the nail shank itself. In this case, the rubber in the underlayment will actually stick to the ridges in the nail shank and stretch around the nail shank thereby creating a generally watertight seal around the shank of the nail. Without the “self-healing” properties of the rubberized asphalt layer 14 of the underlayment 10 of the present invention, persistent roof leaks abound.

In the preferred embodiment, the rubber includes “SBS” radial rubber although linear rubber, in a higher content percentage, would also be acceptable. The SBS rubber is mixed with the flux asphalt using a high shear mill, as is well known in the art. The rubberized asphalt layer 14 is applied to only one side of the fibrous mat 12. This one-sided application serves to vaporize and drive out any moisture trapped in the fibrous mat 12. Examples of how to coat fibrous mats on one side can be found in the two referenced United States patents previously fully incorporated by reference.

The rubberized asphalt layer 14 infiltrates at least partially but also can extend fully into the central region 13 of fibrous mat 12.

After the application of the rubberized asphalt layer 14 to one side of the fibrous mat 12, oxidized asphalt layers 16 a and 16 b are applied; with oxidized asphalt layer 16 a applied over the rubberized asphalt layer 14 while the oxidized asphalt layer 16 b is applied directly to the fibrous mat on the side opposite the rubberized asphalt layer 14. Accordingly, in the preferred embodiment, the interface between the rubberized asphalt layer 14 and the oxidized asphalt layer 16 b will occur in region 13 of fibrous mat 12 and not proximate or on the upper surface 15 of fibrous mat 12. If the interface between the oxidized asphalt layer 16 b and the rubberized asphalt layer 14 is proximate or at the upper surface 15 of fibrous mat 12, the oxidized asphalt layer 16 exhibits a tendency to slip or shear away from the rubberized asphalt layer particularly due to foot traffic when the product was installed on a hot roof. This presents a dangerous situation and also one where the product would have a tendency to adhere to an adjacent layer.

As is well known in the prior art, an oxidized asphalt layer typically includes approximately 50% oxidized asphalt and 50% filler. The oxidized asphalt layer 16 b will become the top surface of the underlayment 10. Since there is no rubberized asphalt layer under the oxidized asphalt layer 16 b, anyone walking on this product will not slip given the propensity of oxidized asphalt layer to break away from the rubberized asphalt layer if the rubberized asphalt later were located directly beneath the top oxidized asphalt layer and not within the fibrous mat 12.

Finally, the top and bottom of the underlayment 10 is coated with a talc acrylic layer 18. The talc acrylic layer 18 provides an additional coating to the oxidized asphalt layers, filling in any voids that are present and preventing the membrane from sticking to itself when the rolled. The talc layer 18 is applied as a talc/water or talc polymer mixture as described, for example, in U.S. Pat. No. 6,531,200. In an alternative embodiment, talc layer 18 a may be replaced with or include granular particles.

Accordingly, the present invention provides a novel and useful underlayment product which can be used under many roofing or other materials as a substrate or underlayment, in which serves to self-seal around any penetrations such as nails and the like.

As mentioned above, the present invention is not intended to be limited to a system or method which must satisfy one or more of any stated or implied object or feature of the invention and should not be limited to the preferred, exemplary, or primary embodiment(s) described herein. Modifications and substitutions by one of ordinary skill in the art are considered to be within the scope of the present invention, which is not to be limited except by the allowed claims. 

1. An underlayment membrane comprising: a fibrous mat having an upper surface and a lower surface; a rubberized asphalt coating applied to the lower surface of the fibrous mat and extending at least partially into said fibrous mat; and an oxidized asphalt coating applied to said upper and lower surfaces of said fibrous mat generally encapsulating said upper and lower surfaces of said mat including said rubberized asphalt coating applied to the lower surface of the fibrous mat.
 2. The underlayment membrane of claim 1 further including a release coating applied to said oxidized asphalt coating proximate said upper and lower surfaces of said fibrous mat.
 3. The underlayment membrane of claim 2 wherein said release coating includes a talc coating.
 4. The underlayment membrane of claim 2 wherein said release coating includes granule particles applied proximate at least said oxidized asphalt coating proximate said upper surface of said fibrous mat.
 5. The underlayment membrane of claim 2 wherein said release coating includes a polymeric coating disposed on at least said oxidized asphalt coating proximate said upper surface of said fibrous mat.
 6. The underlayment membrane of claim 5 wherein said polymeric coating is provided with a coating of finally-ground mineral.
 7. The underlayment membrane of claim 6 wherein said finally-ground mineral includes talc.
 8. The underlayment membrane of claim 6 wherein said finally-ground mineral includes granules.
 9. The underlayment membrane of claim 1 wherein said rubberized asphalt coating includes approximately 46% flux asphalt, 4% rubber and 50% filler material.
 10. The underlayment membrane of claim 1 wherein the fibrous mat includes fibers selected from the group consisting of polyesters, polypropylenes and fiberglass.
 11. An underlayment membrane comprising: a fibrous mat having an upper surface and a lower surface; a rubberized asphalt coating applied to the lower surface of the fibrous mat and extending at least partially into said fibrous mat; an oxidized asphalt coating applied to said upper and lower surfaces of said fibrous mat generally encapsulating said upper and lower surfaces of said mat including said rubberized asphalt coating applied to the lower surface of the fibrous mat; and a release coating applied to said oxidized asphalt coating proximate said upper and lower surfaces of said fibrous mat.
 12. An underlayment membrane comprising: a fibrous mat having an upper surface and a lower surface; a rubberized asphalt coating applied to the lower surface of the fibrous mat and extending only partially into said fibrous mat; and an oxidized asphalt coating applied to said upper and lower surfaces of said fibrous mat generally encapsulating said upper and lower surfaces of said mat including said rubberized asphalt coating applied to the lower surface of the fibrous mat. 